Patients inflicted with cataracts in one or both eyes must sometimes undergo corrective treatment to remove the cataracts. Prior to corrective treatment, the cataract patient finds, typically, that his vision deteriorates over a period of time. Generally, prescription lenses are worn to provide optimum acuity. These lenses, however, do not fully correct the imaging capability of the eye.
Cataracts have a light-scattering effect so that the light entering the eye through a wide angle is spread over the retina. The light-scattering effect resulting from the cataract reduces the contrast of images viewed, thus making such images appear blurred. This is a particularly serious problem in higher ambient light conditions, such as on beaches and on bright, sunshiny days. Also, at night, headlights of cars flood the eyes with light. Normal eyes, when directed to the road, are only minimally affected. However, the light from the headlights of cars is scattered by cataracts and presents a problem to cataract patients wishing to drive at night.
In my earlier patent, Byler U.S. Pat. No. 4,012,129, there is disclosed an optical device for pre-operative cataract patients comprising an opaque mask attached to spectacle frames or other means for mounting before the eyes. The mask includes a horizontally extending slotted transparent area or opening through which the patient's vision is unobstructed. The mask further includes an array of transparent areas or openings disposed below the slotted opening. The size and positioning of the areas or openings of the array are interrelated with the slotted opening to provide an increased vertical field of vision while restricting the light striking the patient's eye to a minimum.
Under certain conditions, an opaque mask such as related by the Byler '129 patent may restrict the user's clear field of vision. Specifically, a narrow horizontal area can restrict the user's clear field of vision through the side portions of the mask. The restriction of the side vision is an especially important consideration when the user is in a mobile situation, such as driving, which requires constant adjustment.